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Meta-Analysis of Carbohydrate Solution Intake during Prolonged Exercise in Adults: From the Last 45+ Years' Perspective.
Bourdas, DI, Souglis, A, Zacharakis, ED, Geladas, ND, Travlos, AK
Nutrients. 2021;(12)
Abstract
Carbohydrate (CHO) supplementation during prolonged exercise postpones fatigue. However, the optimum administration timing, dosage, type of CHO intake, and possible interaction of the ergogenic effect with athletes' cardiorespiratory fitness (CRF) are not clear. Ninety-six studies (from relevant databases based on predefined eligibility criteria) were selected for meta-analysis to investigate the acute effect of ≤20% CHO solutions on prolonged exercise performance. The between-subject standardized mean difference [SMD = ([mean post-value treatment group-mean post-value control group]/pooled variance)] was assessed. Overall, SMD [95% CI] of 0.43 [0.35, 0.51] was significant (p < 0.001). Subgroup analysis showed that SMD was reduced as the subjects' CRF level increased, with a 6-8% CHO solution composed of GL:FRU improving performance (exercise: 1-4 h); administration during the event led to a superior performance compared to administration before the exercise, with a 6-8% single-source CHO solution increasing performance in intermittent and 'stop and start' sports and an ~6% CHO solution appearing beneficial for 45-60 min exercises, but there were no significant differences between subjects' gender and age groups, varied CHO concentrations, doses, or types in the effect measurement. The evidence found was sound enough to support the hypothesis that CHO solutions, when ingested during endurance exercise, have ergogenic action and a possible crossover interaction with the subject's CRF.
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Effects of cardiorespiratory fitness and exercise training on cerebrovascular blood flow and reactivity: a systematic review with meta-analyses.
Smith, EC, Pizzey, FK, Askew, CD, Mielke, GI, Ainslie, PN, Coombes, JS, Bailey, TG
American journal of physiology. Heart and circulatory physiology. 2021;(1):H59-H76
Abstract
We address two aims: Aim 1 (Fitness Review) compares the effect of higher cardiorespiratory fitness (CRF) (e.g., endurance athletes) with lower CRF (e.g., sedentary adults) on cerebrovascular outcomes, including middle cerebral artery velocity (MCAv), cerebrovascular reactivity and resistance, and global cerebral blood flow, as assessed by transcranial Doppler (TCD) or magnetic resonance imaging (MRI). Aim 2 (Exercise Training Review) determines the effect of exercise training on cerebrovascular outcomes. Systematic review of studies with meta-analyses where appropriate. Certainty of evidence was assessed by the Grading of Recommendations Assessment, Development, and Evaluation (GRADE). Twenty studies (18 using TCD) met the eligibility criteria for Aim 1, and 14 studies (8 by TCD) were included for Aim 2. There was a significant effect of higher CRF compared with lower CRF on cerebrovascular resistance (effect size = -0.54, 95% confidence interval = -0.91 to -0.16) and cerebrovascular reactivity (0.98, 0.41-1.55). Studies including males only demonstrated a greater effect of higher CRF on cerebrovascular resistance than mixed or female studies (male only: -0.69, -1.06 to -0.32; mixed and female studies: 0.10, -0.28 to 0.49). Exercise training did not increase MCAv (0.05, -0.21 to 0.31) but showed a small nonsignificant improvement in cerebrovascular reactivity (0.60, -0.08 to 1.28; P = 0.09). Exercise training showed heterogeneous effects on regional but little effect on global cerebral blood flow as measured by MRI. High CRF positively effects cerebrovascular function, including decreased cerebrovascular resistance and increased cerebrovascular reactivity; however, global cerebral blood flow and MCAv are primarily unchanged following an exercise intervention in healthy and clinical populations.NEW & NOTEWORTHY Higher cardiorespiratory fitness is associated with lower cerebrovascular resistance and elevated cerebrovascular reactivity at rest. Only adults with a true-high fitness based on normative data exhibited elevated middle cerebral artery velocity. The positive effect of higher compared with lower cardiorespiratory fitness on resting cerebrovascular resistance was more evident in male-only studies when compared with mixed or female-only studies. A period of exercise training resulted in negligible changes in middle cerebral artery velocity and global cerebral blood flow, with potential for improvements in cerebrovascular reactivity.
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Association of Cardiorespiratory Fitness Levels During Youth With Health Risk Later in Life: A Systematic Review and Meta-analysis.
García-Hermoso, A, Ramírez-Vélez, R, García-Alonso, Y, Alonso-Martínez, AM, Izquierdo, M
JAMA pediatrics. 2020;(10):952-960
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Abstract
IMPORTANCE Although the associations between cardiorespiratory fitness (CRF) and health in adults are well understood, to date, no systematic review has quantitatively examined the association between CRF during youth and health parameters later in life. OBJECTIVES To examine the prospective association between CRF in childhood and adolescence and future health status and to assess whether changes in CRF are associated with future health status at least 1 year later. DATA SOURCES For this systematic review and meta-analysis, MEDLINE, Embase, and SPORTDiscus electronic databases were searched for relevant articles published from database inception to January 30, 2020. STUDY SELECTION The following inclusion criteria were used: CRF measured using a validated test and assessed at baseline and/or its change from baseline to the end of follow-up, healthy population with a mean age of 3 to 18 years at baseline, and prospective cohort design with a follow-up period of at least 1 year. DATA EXTRACTION AND SYNTHESIS Data were processed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Random-effects models were used to estimate the pooled effect size. MAIN OUTCOMES AND MEASURES Anthropometric and adiposity measurements and cardiometabolic health parameters. RESULTS Fifty-five studies were included with a total of 37 563 youths (46% female). Weak-moderate associations were found between CRF at baseline and body mass index (r = -0.11; 95% CI, -0.18 to -0.04; I2 = 59.03), waist circumference (r = -0.29; 95% CI, -0.42 to -0.14; I2 = 69.42), skinfold thickness (r = -0.34; 95% CI, -0.41 to -0.26; I2 = 83.87), obesity (r = -0.15; 95% CI, -0.23 to -0.06; I2 = 86.75), total cholesterol level (r = -0.12; 95% CI, -0.19 to -0.05; I2 = 75.81), high-density lipoprotein cholesterol (HDL-C) level (r = 0.11; 95% CI, 0.05-0.18; I2 = 69.06), total cholesterol to HDL-C ratio (r = -0.19; 95% CI, -0.26 to -0.13; I2 = 67.07), triglyceride levels (r = -0.10; 95% CI, -0.18 to -0.02; I2 = 73.43), homeostasis model assessment for insulin resistance (r = -0.12; 95% CI, -0.18 to -0.06; I2 = 68.26), fasting insulin level (r = -0.07; 95% CI, -0.11 to -0.03; I2 = 0), and cardiometabolic risk (r = -0.18; 95% CI, -0.29 to -0.07; I2 = 90.61) at follow-up. Meta-regression analyses found that early associations in waist circumference (β = 0.014; 95% CI, 0.002-0.026), skinfold thickness (β = 0.006; 95% CI, 0.002-0.011), HDL-C level (β = -0.006; 95% CI, -0.011 to -0.001), triglyceride levels (β = 0.009; 95% CI, 0.004-0.014), and cardiometabolic risk (β = 0.007; 95% CI, 0.003-0.011) from baseline to follow-up dissipated over time. Weak-moderate associations were found between change in CRF and body mass index (r = -0.17; 95% CI, -0.24 to -0.11; I2 = 39.65), skinfold thickness (r = -0.36; 95% CI, -0.58 to -0.09; I2 = 96.84), obesity (r = -0.21; 95% CI, -0.35 to -0.06; I2 = 91.08), HDL-C level (r = 0.05; 95% CI, 0.02-0.08; I2 = 0), low-density lipoprotein cholesterol level (r = -0.06; 95% CI, -0.11 to -0.01; I2 = 58.94), and cardiometabolic risk (r = -0.08; 95% CI, -0.15 to -0.02; I2 = 69.53) later in life. CONCLUSIONS AND RELEVANCE This study suggests that early intervention and prevention strategies that target youth CRF may be associated with maintaining health parameters in later life.
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Cycling and cardiovascular disease risk factors including body composition, blood lipids and cardiorespiratory fitness analysed as continuous variables: Part 2-systematic review with meta-analysis.
Nordengen, S, Andersen, LB, Solbraa, AK, Riiser, A
British journal of sports medicine. 2019;(14):879-885
Abstract
OBJECTIVES We aimed to examine the relationship between cycling (particularly commuter cycling) and risk factors associated with cardiovascular diseases (CVDs) including body composition, blood lipids and cardiorespiratory fitness. This study differed from our recent (Part 1) systematic review in that risk factors for CVD were analysed as continuous variables rather than being present or absent. DESIGN Systematic review and meta-analysis. ELIGIBILITY CRITERIA We searched four databases (Web of Science, MEDLINE, SPORTDiscus and Scopus). All quantitative studies, published until August 2017, were included when a general population was investigated, cycling was assessed either in total or as a transportation mode, and CVD risk factors were reported. METHODS We analysed body composition, physical activity (PA), cardiorespiratory fitness (CRF), blood lipids and blood pressure (BP). Skinfold, waist circumference and body mass index were analysed and prioritised in that order when more than one measure were available. PA included measures of counts per minutes, moderate-to-vigorous PA or minutes per week. CRF included results of maximal tests with or without expired air or submaximal test. For blood lipids and BP, separate analyses were run for low-density and high-density lipoprotein, triglycerides, total cholesterol, systolic BP and diastolic BP. Studies were excluded when reporting dichotomous outcomes or when cycling and walking were combined. Heterogeneity was investigated using I2. RESULTS Fifteen studies were included; the majority reported commuter cycling. In total, we included 5775 cyclists and 39 273 non-cyclists. Cyclists had more favourable risk factor levels in body composition -0.08 (95% CI -0.13 to -0.04), PA 0.13 (95% CI 0.06 to 0.20), CRF 0.28 (95% CI 0.22 to 0.35) and blood lipids compared with non-cyclists. There was no sex difference in risk reduction. CONCLUSION/IMPLICATION Cycling mitigated the risk factor profile for CVD. A strength of this systematic review is that all the risk factors were analysed as continuous variables. These data provide evidence for practitioners, stakeholders, policy-makers and city planners to accommodate and promote cycling. SYSTEMATIC REVIEW REGISTRATION PROSPERO CRD42016052421.
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The effect of high Intensity interval training versus moderate intensity continuous training on arterial stiffness and 24h blood pressure responses: A systematic review and meta-analysis.
Way, KL, Sultana, RN, Sabag, A, Baker, MK, Johnson, NA
Journal of science and medicine in sport. 2019;(4):385-391
Abstract
OBJECTIVES Greater arterial stiffness and poor 24h blood pressure (BP) are recognized as indicators of poor cardiovascular health. Evidence has shown that high intensity interval training (HIIT) may be a superior alternative to moderate intensity continuous training (MICT) for improving cardiovascular disease risk factors such as cardiorespiratory fitness and vascular function. However, there are limited data comparing the effect of HIIT to MICT on central arterial stiffness and/or 24h BP response. The purpose of this study was to compare HIIT versus MICT on central arterial stiffness and 24h BP outcomes by systematic review and meta-analysis. DESIGN A systematic review and meta-analysis was conducted. METHODS Eligible studies were exercise training interventions (≥4weeks) that included both HIIT and MICT and reported central arterial stiffness, as measured by pulse wave velocity and augmentation index and/or 24h BP outcome measures. RESULTS HIIT was found to be superior to MICT for reducing night-time diastolic BP (ES: -0.456, 95% CI: -0.826 to -0.086mmHg; P=0.016). A near-significant greater reduction in daytime systolic (ES: -0.349, 95% CI: -0.740 to 0.041mmHg; p=0.079) and diastolic BP was observed with HIIT compared to MICT (ES: -0.349, 95% CI: -0.717 to 0.020mmHg; p=0.063). No significant difference was found for other BP responses or arterial stiffness outcomes. CONCLUSIONS HIIT leads to a superior reduction in night-time diastolic BP compared to MICT. Furthermore, a near-significant greater reduction in daytime BP was found with HIIT compared to MICT. No significant difference was observed for changes to central arterial stiffness between HIIT and MICT.
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The effect of progressive resistance training on aerobic fitness and strength in adults with coronary heart disease: A systematic review and meta-analysis of randomised controlled trials.
Hollings, M, Mavros, Y, Freeston, J, Fiatarone Singh, M
European journal of preventive cardiology. 2017;(12):1242-1259
Abstract
Design We aimed to evaluate the effect of progressive resistance training on cardiorespiratory fitness and muscular strength in coronary heart disease, when compared to control or aerobic training, and when combined with aerobic training. Secondary aims were to evaluate the safety and efficacy of progressive resistance training on other physiological and clinical outcomes. Methods and results Electronic databases were searched from inception until July 2016. Designs included progressive resistance training vs control, progressive resistance training vs aerobic training, and combined training vs aerobic training. From 268,778 titles, 34 studies were included (1940 participants; 71.9% male; age 60 ± 7 years). Progressive resistance training was more effective than control for lower (standardized mean difference 0.57, 95% confidence interval (0.17-0.96)) and upper (1.43 (0.73-2.13)) body strength. Aerobic fitness improved similarly after progressive resistance training (16.9%) or aerobic training (21.0%); (standardized mean difference -0.13, 95% confidence interval (-0.35-0.08)). Combined training was more effective than aerobic training for aerobic fitness (0.21 (0.09-0.34), lower (0.62 (0.32-0.92)) and upper (0.51 (0.27-0.74)) body strength. Twenty studies reported adverse event information, with five reporting 64 cardiovascular complications, 63 during aerobic training. Conclusion Isolated progressive resistance training resulted in an increase in lower and upper body strength, and improved aerobic fitness to a similar degree as aerobic training in coronary heart disease cohorts. Importantly, when progressive resistance training was added to aerobic training, effects on both fitness and strength were enhanced compared to aerobic training alone. Reporting of adverse events was poor, and clinical gaps were identified for women, older adults, high intensity progressive resistance training and long-term outcomes, warranting future trials to confirm safety and effectiveness.
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Cardiorespiratory Fitness and Adiposity as Determinants of Metabolic Health-Pooled Analysis of Two Twin Cohorts.
Jukarainen, S, Holst, R, Dalgård, C, Piirilä, P, Lundbom, J, Hakkarainen, A, Lundbom, N, Rissanen, A, Kaprio, J, Kyvik, KO, et al
The Journal of clinical endocrinology and metabolism. 2017;(5):1520-1528
Abstract
CONTEXT The joint effects of cardiorespiratory fitness (CRF) and body composition on metabolic health are not well known. OBJECTIVE To examine the associations of CRF, fat-free mass index (FFMI), and fat mass index (FMI) with metabolic health in individual twins and controlling for genetic and shared environmental effects by studying monozygotic intrapair differences. DESIGN, SETTING, AND PARTICIPANTS Two cross-sectional samples of healthy adult monozygotic and dizygotic twins were drawn from population-based Danish and Finnish national twin registries (n = 996 and n = 309). MAIN MEASURES CRF was defined as VO2max divided by fat-free mass. Insulin sensitivity and acute insulin response indices were derived from an oral glucose tolerance test. A continuous metabolic syndrome score was calculated. Visceral and liver fat were measured in the Finnish sample. Associations were analyzed separately in both cohorts with multivariate linear regression and aggregated with meta-analytic methods. RESULTS Insulin sensitivity, acute insulin response, metabolic syndrome score, visceral, and liver fat amount had strong and statistically significant associations with FMI (|β| 0.53 to 0.79), whereas their associations with CRF and FFMI were at most weak (|β| 0.02 to 0.15). The results of the monozygotic intrapair differences analysis showed the same pattern. CONCLUSIONS Although FMI is strongly associated with worsening of metabolic health traits, even after controlling for genetic and shared environmental factors, there was little evidence for the effects of CRF or FFMI on metabolic health. This suggests that changing FMI rather than CRF or FFMI may affect metabolic health irrespective of genetic or early environmental determinants.